Transmission of Influenza on International Flights | CDC EID

EID Journal Home > Volume 17, Number 7–July 2011
Volume 17, Number 7–July 2011
Research
Transmission of Influenza on International Flights, May 2009
A. Ruth Foxwell, Leslee Roberts, Kamalini Lokuge, and Paul M. Kelly Author affiliations: Department of Health and Ageing, Canberra, Australian Capital Territory, Australia (A.R. Foxwell, L. Roberts); Australian National University, Canberra (A.R. Foxwell, L. Roberts, K. Lokuge, P.M. Kelly); and ACT Government Health Directorate, Canberra (P.M. Kelly)

Suggested citation for this article


Abstract
Understanding the dynamics of influenza transmission on international flights is necessary for prioritizing public health response to pandemic incursions. A retrospective cohort study to ascertain in-flight transmission of pandemic (H1N1) 2009 and influenza-like illness (ILI) was undertaken for 2 long-haul flights entering Australia during May 2009. Combined results, including survey responses from 319 (43%) of 738 passengers, showed that 13 (2%) had an ILI in flight and an ILI developed in 32 (5%) passengers during the first week post arrival. Passengers were at 3.6% increased risk of contracting pandemic (H1N1) 2009 if they sat in the same row as or within 2 rows of persons who were symptomatic preflight. A closer exposed zone (2 seats in front, 2 seats behind, and 2 seats either side) increased the risk for postflight disease to 7.7%. Efficiency of contact tracing without compromising the effectiveness of the public health intervention might be improved by limiting the exposed zone.

The emergence of pandemic influenza A (H1N1) 2009 in Mexico and the United States, with rapid spread to Europe, Asia, and the Pacific, is testament to the ease of spread of infectious disease across the globe (1). The World Health Organization activated level 5 pandemic alert on April 29, 2009, when sustained community transmission of the pandemic virus was demonstrated in Mexico and the United States. In her address to the United Nations on May 4, 2009, Margaret Chan, Director-General of the World Health Organization, called for heightened vigilance to limit international spread of the virus (2). Australia's response was rapid, with the introduction of a number of measures as outlined in the Australian Health Management Plan for Pandemic Influenza, 2008 (3). These measures included in-flight messages to incoming passengers, use of health declaration cards by all incoming travelers, and mandatory reporting by the pilot on the health status of crew and passengers before landing (4). The novel virus was also listed as a quarantinable disease under Australia's Quarantine Act 1908, which allows for the application of public health powers for intervention (5).

Reports documenting spread of disease during airline flight are limited (6–9). Specific policy stating that passengers sitting in the same row as and within 2 rows of a confirmed case-patient should be treated as suspected of having that disease relies on studies of air travel where the index case-patient was infected with Mycobacterium tuberculosis (10–12). The aim of this study was to investigate the spread of pandemic (H1N1) 2009 infection from persons with confirmed disease on flights to Australia during May 2009. The spread of other influenza-like illness (ILI) was also documented.

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Transmission of Influenza on International Flights CDC EID

Suggested Citation for this Article
Foxwell AR, Roberts L, Lokuge K, Kelly PM. Transmission of influenza-like illness on international flights, May 2009. Emerg Infect Dis [serial on the Internet]. 2011 Jul [date cited]. http://www.cdc.gov/EID/content/17/7/1188.htm

DOI: 10.3201/eid1707.101135
Comments to the Authors
Please use the form below to submit correspondence to the authors or contact them at the following address:
Paul M. Kelly, ACT Government Health Directorate, Canberra, ACT, Australia; email: paul.kelly@act.gov.au